// 屏幕滚动
function scroll() {
	if (window.pageXOffset != undefined) {
		return {
			"left": window.pageXOffset,
			"top": window.pageYOffset
		}
	} else if (document.compatMode != 'BackCompat') {
		return {
			"left": document.body.scrollLeft,
			"top": document.body.scrollTop
		}
	} else {
		return {
			"left": document.documentElement.scrollLeft,
			"top": document.documentElement.scrollTop
		}
	}
}